Why cooled CCD camera?

The dynamic range of a camera is an important parameter of the image quality. Noise can reduce the dynamic range of the camera dramatically. Cooling helps to produce a higher quality image.

Thermal Noise

Thermal noise is directly related to the exposure time of an image. The longer the exposure time, the higher the noise that is collected by the pixel. For very long exposure times you can get the effect of "hot spots" on the CCD. Basically when a CCD is exposed longer, more and more pixels turn out to be white. For long exposure times, cooling the CCD chip is very important because the thermal noise can be reduced. For exposure times longer than 0.5 seconds a cooled camera is recommended.

Electronic Noise

Electronic noise influences all images independent of the exposure time. Electronic noise is related to electronic design and the read out frequency of the sensor.